In general, as a measurement instrument or as a measurement method for measurement of particles, it has been known to use a particle mass counter for counting the particle mass of particles.
An FCAE (Faraday Cup Aerosol Electrometer) and a PM sensor, as described in Japanese Laid-Open Patent Publication No. 2012-194078, are examples of such a particle mass counter.
A CPC (Condensation Particle Counter), as described in Japanese Laid-Open Patent Publication No. 2012-026892, is an example of a particle counter for counting the number of particles. In such a CPC, organic gases of alcohol, butanol, etc., are mixed in a saturated state and adhered to particles in the exhaust gas. The particles grow to have an increased particle size. Following growth of the particles, the particles are discharged through slits. Then, laser light is irradiated onto the discharged particles in order to count the number of particles.